Featured Research

Fecal source tracking in Norwegian water catchments: New methods

Date:

June 6, 2014

Source:

Bioforsk - Norwegian Institute for Agricultural and Environmental Research

Summary:

A set of methods for the detection of fecal pollution in Norwegian watercourses has been tested and implemented. The methods, which combine microbial and molecular biological techniques, can give answers as to whether the contamination is a result of human or animal excreta. In addition, the methods provide grounds for assessing whether the water pollution poses a health risk or not.

The Norwegian Institute for Agricultural and Environmental Research, Bioforsk, has tested and implemented a set of methods for the detection of fecal pollution in Norwegian watercourses. The methods, which combine microbial and molecular biological techniques, can give answers as to whether the contamination is a result of human or animal excreta. In addition, the methods provide grounds for assessing whether the water pollution poses a health risk or not.

Related Articles

Fecal contamination in water is one of the most common reasons for human diseases. Molecular methods can reveal if the contaminants derive from human or animal excreta. The methods also provide a basis for determining whether water contamination constitutes a health risk or not.

Fecal water contamination occurs when excreta from humans or animals enter a water source due to e.g. sewage leakage or inadequate wastewater treatment.

As of today, it has not been customary in Norway to specify whether the contamination source derives from humans or animals. This has made it difficult to implement efficient measures against fecal water contamination, which in return makes it difficult to reduce contaminant exposure and potential health risks associated with it.

This is about to change. The Norwegian Institute for Agricultural and Environmental Research, Bioforsk, has tested and implemented a set of methods for the detection of fecal pollution in Norwegian watercourses. The methods, which combine microbial and molecular biological techniques, can give answers as to whether the contamination is a result of human or animal excreta. In addition, the methods provide grounds for assessing whether the water pollution poses a health risk or not.

E. coli as indicator for fecal contamination

Fecal contamination measured in terms of the indicator bacteria E. coli can be the result of wastewater leakage, effluent discharge after inefficient sewage treatment, or agricultural runoff containing animal fecal matter entering surface and/or groundwater. The contamination happens if E. coli enters water, either directly from the contaminative source, or indirectly via e.g. soil irrigation with fecally contaminated water or use of organic animal-based fertilizers. The latter is particularly a problem after heavy rainfall with subsequent runoff.

Most strains of E. coli are harmless, but some groups, such as Shiga toxin-producing E. coli, STEC, contain types of E. coli which are particularly pathogenic. STEC is also the only group of E. coli which is transmitted from animals to humans through food and waterborne infection. It is therefore important that e.g. drinking water does not contain it.

Two-step method for contaminant detection

Adam Paruch from Bioforsk is one of the researchers involved in the testing of the new methods for determining the source of fecal contamination in water. He points out that there are several microbial methods for the detection of E. coli in water, but up until now, it has not been common practice in Norway to use molecular biology to determine exactly where these bacteria stem from, i.e. whether the source is human or animal. This has rendered it difficult to implement effective and target-specific measures against the contaminative source.

"The tool set for tracking contaminative sources consist of two steps. The first is to perform a microbiological test to determine whether a water source is affected by fecal contaminants or not. To do this we carry out a standard 18-hour test for the detection and quantification of E. coli in water samples. In the second step, which is based on genetic markers, we only concentrate on the fecally positive water samples from the first step. The well characterized host associated markers, e.g. for humans, cows and horses, can be detected both qualitatively and quantitatively. This helps us to quickly identify the major sources of contamination in a water catchment, " Paruch says.

He has collaborated closely with Lisa Paruch, a molecular biologist at Bioforsk, in testing the tool set on various smaller catchments in Norway. The results obtained so far clearly indicate that molecular analyses can be very useful for determining the specific source of fecal contaminants in water.

Methods reveal health risk potential of bacteria

In addition to fecal origin discrimination (i.e. human vs. non-human) and further identification of principle pollutants, the two researchers' analyses also included another test which rendered it possible to determine whether the bacteria present in water was pathogenic or not.

"The molecular methods used in our experiments can determine the seven most common STEC serogroups, which includes E. coli O157:H7 which induces serious illnesses and even deaths among humans. By combining microbial and molecular biological techniques, we are in the process of establishing an efficient analyses set which can provide us with exclusive supporting information for public health risk assessment," Lisa Paruch says.

Call for collaboration with authorities

In Norway, this is the first time molecular and microbial biological methods are combined in a tool set to track sources of fecal contamination in water. As of today, the methods have only been tested on a few small catchments. The plan now is to invite Norwegian environmental authorities and municipalities suffering from contaminative waters in partaking in collaborative efforts to test the methods further.

"We know that fecal contamination doesn't only derive from wastewater, so for the appropriate measures to be implemented, it is important that we find out what the actual contamination source is. Now we have established a tool set of methods which can provide us with information on this," says Trond Mæhlum, Head of Department at Bioforsk Soil and Environment.

"By implementing host-specific genetic markers from e.g. cows, horses, pigs and birds in a standard analyses set, we can use these methods to find out which target-specific measures need to be implemented to limit the discharge of fecal contaminants to waters. This can protect humans and our environment from potentially pathogenic E. coli from human and animal feces. Our hope is that authorities working with environmental, health and food security issues are interested in testing and implementing these methods further in cooperation with us," he says.

More From ScienceDaily

More Earth & Climate News

Featured Research

Mar. 31, 2015  Soil organic matter, long thought to be a semi-permanent storehouse for ancient carbon, may be much more vulnerable to climate change than previously thought. Scientists have found that the common ... full story

Mar. 31, 2015  The ocean is a large reservoir of dissolved organic molecules, and many of these molecules are stable against microbial utilization for hundreds to thousands of years. They contain a similar amount ... full story

Mar. 31, 2015  Using the assessment tool ForWarn, US Forest Service researchers can monitor the growth and development of vegetation that signals winter's end and the awakening of a new growing season. Now these ... full story

Mar. 31, 2015  Geoscientists have revealed information about how continents were generated on Earth more than 2.5 billion years ago -- and how those processes have continued within the last 70 million years to ... full story

Mar. 31, 2015  Until now electric fences and trenches have proved to be the most effective way of protecting farms and villages from night time raids by hungry elephants. But researchers think they may have come up ... full story

Mar. 31, 2015  The volcanologist Stephen Self, an expert on super-eruptions, was the first modern-day scientist to visit Tambora in Indonesia, the site of the largest volcanic eruption in 1,000 years. On the 200th ... full story

Mar. 31, 2015  Researchers have detected a human fingerprint deep in the Borneo rainforest in Southeast Asia. Cold winds blowing from the north carry industrial pollutants from East Asia to the equator, with ... full story

Mar. 31, 2015  Landfills can make a profit from all their rotting waste and a new patent explains exactly how to make the most out of the stinky garbage sites. Decomposing trash produces methane, a landfill gas ... full story

Mar. 31, 2015  As the five-year anniversary of the explosion of the Deepwater Horizon oil rig approaches, a new report looks at how twenty species of wildlife are faring in the aftermath of the ... full story

Mar. 31, 2015  Accurately anticipating an approaching typhoon's destructive force makes all the difference in advance preparations and as a consequence, the cost in lives. But over the decades, climate scientists ... full story

Related Stories

May 6, 2014  Although water from improved sources (such as piped water and bore holes) is less likely to contain fecal contamination than water from unimproved sources, improved sources in low- and middle-income ... full story

Jan. 14, 2011  A simple, automated method of tracking E. coli uses a laser to detect and monitor the microbe in potentially contaminated bodies of water or waterways. The technique could reduce the incidence of ... full story

Sep. 20, 2010  Building good fences could make our water cleaner, and help us to meet European standards, according to new research. Scientists have created a computer model to investigate the problem of faecal ... full story

May 5, 2010  Scientists are reporting dramatic new real-world evidence supporting the idea that hand washing can prevent the spread of water-borne disease. It appears in a new study showing a connection between ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.